JP2000054850A - Engine supercharging system - Google Patents

Abstract

(57) [Abstract] [Problem] To improve low-speed torque and acceleration response of a turbocharged engine. SOLUTION: An impeller of a form basically similar to an impeller used for a vortex blower having a characteristic of a small air volume and a high wind pressure that can obtain a high pressure coefficient at a low specific speed is used for a turbine and a blower. A second supercharger is configured and used as an auxiliary supercharger of a turbocharger which is the first supercharger.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a supercharging system for recovering exhaust energy of an engine by using a turbocharger, boosting intake air, supplying the boosted intake air to the engine, and increasing the specific output of the engine.

[0002]

2. Description of the Related Art As a supercharger for an automobile engine, a turbocharger comprising an exhaust turbine and a centrifugal compressor, a roots type called a supercharger, a resholm type (screw type), a scroll type (spiral type)
Are well known. There is also known a pressure wave type supercharger of a type in which intake air is compressed using a pressure wave of exhaust gas or a supercharger called a complex device.

[0003] The turbocharger rotates the turbine at the exhaust gas pressure and rotates the coaxially mounted centrifugal impeller to compress the intake air. The turbocharger can recover the energy of the exhaust gas. Sufficient supercharging cannot be obtained in the low engine speed range of the engine with less power. The problem with turbocharged engines is the lack of low speed torque and poor acceleration response.

On the other hand, a supercharger or a pressure wave type supercharger using a positive displacement compressor can provide a sufficient supercharge even in a low rotation range, but is driven by a belt or the like on an engine.
It consumes a part of the engine power and is not suitable for improving the specific output at medium and high speed rotation. Therefore, recently, for example, Journal of the Gas Turbine Society of Japan Vol. 24, No. 96 (Mar. 1997 Turbocharger Special Edition), p19 to p20, p26 to p28
The variable nozzle turbocharger introduced in the above has been developed.

[0005] This is a turbocharger in which the angle of a cascade nozzle provided on the exhaust gas inflow side of a turbine is variable, and is called a VT or VG turbo. This is an improvement in the characteristics of the turbine at low flow rates by changing the angle of the nozzle, and it is true that the engine torque is improved over the whole range of the rotation speed compared with the conventional turbocharger (FIG. 1 on p20).
4). However, the sudden decrease in torque in the low rotation range has not been eliminated.

[0006] In addition, a turbocharger and a supercharger, both of which are introduced in the same magazine, p24, etc., have also been developed, which are called "mechanical supercharged turbo compound system (Fig. 13 of p24)" or "hybrid supercharged system". Have been. As a result, an engine having a flat output characteristic over a wide rotational speed range is realized, but there is no change in consuming engine power in a low rotational speed range.

[0007] Japanese Patent No. 2736861 (Japanese Patent Laid-Open No. 4-25552)
6) In the official gazette, a turbocharger using a substream turbine and a turbocharger using an axial turbine are used together to realize an engine with flat output characteristics over a wide rotation speed range. However, it is effective only when applied to a considerably large-capacity engine in which a turbocharger functions to a certain extent, and is not a general supercharging system applicable to a small engine.

Next, the vortex supercharger used in the present invention will be described. The eddy-current supercharger is described in, for example, “Mechanical Engineering Handbook” applied edition, Fluid Machinery (edited by the Japan Opportunity Society, 1986, Toppan Printing Co., Ltd.), p. ) p2197-2208
Vortex blower, regenerati
This is a supercharger that basically uses the same type of impeller for a turbine and a blower as an impeller used for a fluid machine called a veblower.

That is, an impeller provided with a plurality of blades which are basically formed radially on the outer periphery of a disk-shaped substrate, wherein the blade is provided on only one surface of the outer periphery of the disk and on both surfaces Some are provided. The blower is housed in a casing that forms a ring-shaped fluid passage around the impeller blades,
One partition separating the inlet and the outlet of the fluid is provided in the fluid passage in a shape that does not hinder the rotation of the impeller.

The impeller is rotated by a motor or an engine, sucks a fluid from a fluid inlet provided on one side of the partition wall, applies centrifugal compression several times by a plurality of blades, and raises the pressure. It is discharged from a fluid outlet provided on the side. A high pressure coefficient can be obtained at a low specific speed, that is, a characteristic of a small air volume and a high air pressure. Therefore, good supercharging can be performed even at a low engine speed and a small flow rate.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to make the output characteristics of a turbocharged engine flat over a wide range of rotational speeds, improve low-speed torque and acceleration response, and increase the specific output of the engine, that is, the specific output of the engine. To provide a supercharging system that achieves economic improvement.

[0012]

An object of the present invention is to provide a high pressure coefficient at a low specific velocity, that is, a form basically similar to that of an impeller used in a vortex blower having characteristics of small air volume and high wind pressure. This is achieved by forming a second supercharger using the impeller of (1) for a turbine and a blower, and using this as an auxiliary supercharger of a turbocharger which is a first supercharger.

[0013] Further, the air pressurized by the second supercharger using the vortex type fluid machine type impeller is discharged through an ejector nozzle disposed downstream of the main intake passage. By doing so, supercharging is more effectively achieved over a wide range of rotation speeds.

Further, by providing a second supercharger using an impeller of the vortex type fluid machine type in such a manner that both the intake and exhaust systems are arranged in series with the turbocharger as the first supercharger, supercharging is further improved. Achieved effectively.

Further, two partition walls are provided in one casing to form two fluid passages, and a single vortex-flow type fluid machine type impeller is used for both the turbine and the blower to form a second fluid passage. By configuring the supercharger, a more compact system can be realized.

Further, when the engine is operated at medium to high speeds and medium to high loads, the flow control valves provided in the intake and exhaust systems are each controlled at an intermediate angle, and both the intake and exhaust are controlled by the vortex charger which is the second supercharger. By bypassing, supercharging is more effectively achieved over a wide speed range.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a system configuration diagram of an engine intake / exhaust system showing a first embodiment. Note that the gas flow (arrow) and the states of the valves (valves) 9 and 10 shown in this figure show a case where the engine is operating at a low speed and a high load in this system. 2 is a longitudinal sectional view of the vortex charger 7 shown in FIG. 1, and FIG. 3 is an XX of the configuration shown in FIG.
FIG. 4 is a sectional view taken along a line XI-XI of the configuration shown in FIG. 2.

The exhaust gas of the engine 1 passes through the exhaust pipe 12 from the exhaust manifold 2 and passes through the conventional turbocharger 5.
To rotate the turbine 5b, and rotate the centrifugal blade compressor 5a via the shaft 5c. However, in this state, the exhaust speed is low due to the low rotation of the engine, and the rotation speed of the turbine 5b is low, so that the boosting function as the turbocharger is insufficient.

Therefore, the exhaust gas discharged from the turbine 5b is supplied to the inlet 7 of the vortex charger 7 through a pipe 16.
Lead to i and make this work. At this time, the valve 9 is fully closed. Exhaust passages 7n and 7o are formed around the outer periphery of the vortex turbine impeller 7b by casings 7e and 7f shown in FIG. 2 and a partition wall 7q shown in FIG. , Vortex turbine impeller 7b
To rotate. The two flow paths are communicated with each other at an inlet portion and an outlet portion.

The exhaust gas that has caused the vortex turbine impeller 7b to rotate flows out of the outlet 7j to the pipe 18, and then the catalyst 19,
It is released to the atmosphere through the muffler 20. On the other hand, the intake air is taken into the intake pipe 13 from the intake duct 11 via the air cleaner 4 and is supplied to the centrifugal blade compressor 5 of the turbocharger 5.
flows into a.

However, as described above, the pressure of the discharge air is insufficiently increased.
The system is configured such that the intake air is guided to the blower inlet 7g of the vortex charger 7 through the bypass pipe 15 provided upstream thereof, and further increased in pressure is provided by the vortex blower impeller 7a.

At the outer periphery of the vortex blower impeller 7a, intake passages 71 and 7m are formed by casings 7c and 7d shown in FIG. 2 and a partition wall 7p shown in FIG. 3, and the intake air is supplied from a blower inlet 7g to a blower outlet 7h. , The centrifugal force of several degrees is applied by the impeller 7a to increase the pressure.

At this time, the air flow is a swirling flow (vortex flow) between the grooves between the blades of the impeller 7a and the passages 71 and 7m having an elliptical cross section, and is therefore called a vortex blower. The intake air that has been pressurized and heated is discharged from the blower outlet 7h to the main intake passage 21 through the pipe 17 and the ejector nozzle 30 connected to the pipe 17 and is cooled by the cooler 6, and then is discharged from the intake manifold 3 to the engine. 1
Supplied to

A second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a system configuration diagram of the engine intake / exhaust system, and FIG. 6 is a cross-sectional view illustrating the configuration of the vortex charger 8 in the present embodiment. The gas flow of FIG.
The state of 0 is an operation state in which the engine is running at a low speed and a high load as in FIG. The only difference from the first embodiment is the structure of the swirl charger 8. Although the vortex charger 7 of the first embodiment has a turbine and a blower impeller constituted by two independent impellers, the vortex charger 8 of the present embodiment uses one impeller 8a of the turbine and the blower. It is a configuration used for both.

That is, the first partition wall 8p and the second partition wall 8q are provided inside one casing 8c, and about a half circumference is configured as an exhaust gas passage 8n and about a half circumference is configured as an intake passage 8l. Accordingly, in terms of the rotation direction of the impeller 8a, there is a turbine outlet 8j on the near side of the first partition wall 8p, a blower inlet 8g on the opposite side, and a blower outlet 8 on the near side of the second partition wall 8q.
h, and a turbine inlet 8i is provided on the opposite side.

The high exhaust pressure and the low intake pressure come into contact with each other across the first partition 8p and the second partition 8q. Depending on the method of forming the partitions 8p and 8q, the pressure is further increased by using a pressure wave. Action is also expected.

FIG. 7 shows a low-rotation, low-load engine state which does not require supercharging in the system shown in FIG. 5, in which valves 9 and 10 are fully opened. At this time, the swirl charger 8 hardly operates.

FIG. 8 shows the state of the system shown in FIG. 5 at a medium-high rotation speed and a medium-high load which particularly require supercharging. The opening of the valves 9 and 10 is set at an intermediate position. 5 gives the condition to work effectively. At this time, the exhaust gas discharged from the turbocharger 5 still has residual energy, and the vortex charger 8 can be set by setting the opening degree of the valve appropriately.
This operates because a part of the exhaust gas is bypassed.

At this time, the intake air discharged from the swirl charger 8 to the main intake passage 21 through the ejector nozzle 30 gives an attractive effect to the whole intake air, thereby increasing the absolute flow rate as compared with the case where the swirl charger 8 is not operated. be able to. The state setting shown in FIGS. 7 and 8 is the same in the case of the first embodiment shown in FIG.

FIG. 9 is a diagram comparing the relationship between the rotational speed and the output torque of the engine with the supercharging system and the engine with the conventional turbocharger according to the first embodiment of the present invention. It can be seen that by applying the system of the present invention, the output torque is improved over the entire rotation speed range. Especially 1000 to 1
In the range of 500 rpm, the output torque is improved by about 20%, which is about 10% even with the variable nozzle turbo (Japanese Gas Turbine Society Vol. 24 No. 96 (Mar. 1997)).
In this region, the system of the present invention is superior to the variable nozzle turbo in FIG. 14).

Since the piping is somewhat complicated and disadvantageous in terms of a compact supercharging system, a specific configuration is not shown. However, as a system using the vortex supercharger of the present invention in parallel with a conventional turbocharger. It is also conceivable to configure.

[0032]

According to the present invention, the output characteristics of a conventional turbocharged engine can be improved to be flat over a wide range of rotation speeds, and particularly, low speed torque and acceleration response can be improved, and the specific output of the engine can be improved. , It is possible to achieve improved economic efficiency.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of an engine intake / exhaust system showing a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the vortex charger 7 shown in FIG.

FIG. 3 is a sectional view taken along the line XX of the configuration shown in FIG. 2;

FIG. 4 is a sectional view taken along the line XI-XI of the configuration shown in FIG. 2;

FIG. 5 is a system configuration diagram of an engine intake / exhaust system showing a second embodiment of the present invention.

FIG. 6 is a sectional view showing a configuration of a swirl charger 8 of a second embodiment.

FIG. 7 is a diagram showing a state of low rotation and low load according to the second embodiment.

FIG. 8 is a diagram showing a state of middle-high rotation and middle-high load according to the second embodiment.

FIG. 9 is a comparison diagram of output characteristics between the first embodiment of the present invention and an engine with a conventional turbocharger.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine, 5 ... Turbocharger, 7, 8 ... Eddy-current charger, 7a ... Eddy-current blower impeller, 7b ... Eddy-current turbine impeller, 7p, 7q ... Partition, 8a ... Eddy-current turbine blower impeller, 8p ... First partition , 8q ... second partition,
9,10 ... Valve.

Claims (1)

[Claims] 1. A supercharger system for an engine in which a turbocharger using a centrifugal impeller is used as a first supercharger and a second supercharger is provided to perform auxiliary supercharging. Is a supercharger using a swirl type fluid machine type impeller.